Process for treating tobacco



.July 6, 1937. iv H. L.. SMITH, JR., ET Al. 2,086,446

PROCESS FOR TREATING TOBACCO Filed March 28, 1936 I THERMOMETER TEAM INVENTOR /fw 1. Mtr

BY m01.

ATTORNEY Treatment of tobacco.

Paienfed'luiy c, 11931 I l 2,'86,446 I.

UNITED .STATES 1 PATENT; y' OFFICE i um PROCESS FOR TREATING TOBACCO annee L. smith, Jr., and Lucian N. Jones, melimond, Va., assignors to Thermal Engineering Corporation, Richmond, Va., a' corporation of Application Msi-ch' 2s, i936, serial No. '11,495

19 claim. 4(01. Lal-5s) 'I'his invention relates to a process for treatin! the tobacco is unpacked and results in considertobacco and more'particularly concerns a process able handling of the tabacco leaves prior to steminvolving altering the fmoisture content of ming. Further, with this process, it is diillcult to tobacco. t g produce the exact final moisture content at which i 5 This application is a continuation in part oi' the leaves are best suited for stemming or other 5 our copending application Serial No. 44,156 filed operations. j October 9, 1935 entitled "Process for treating Packed tobacco isequently found to be intobacco and of our copending application Serial tested with worms or other organisms, such as No. 54,443, flied December 14, 1935, entitled the-cigarette beetle or tobacco moth in various At various stages during the preparation and fumiga'tedor otherwise treated 'prior to procshipment of tobacco it is necessary to change essing'. This has in the `past been accomplished its moisture content. Thus, for example, tobacco by treating the tobacco with gases toxic to the for export must have a specifiedf minimum moisorganisms present', and the costs involved in ture content and any excess over this amount fumigation of this type are considerable. More- 15 adds to the shipping cost and export duty thereon, over, knovn fumigating processes, although in whileadeciencyin moisture subjectsthe shipper mostcases effective in killing the worms or into a penalty. sects, frequently fail to kill the eggs from which One of the most important operations in which the organisms develop.

stages of the life cycle, and accordingly, must be 10 moisture is added to tobacco is that known inthe With the above and other considerations in 2'0 art as ordering. After tobacco leaves have been mind, it is proposed in accordance with the prescut and nue or sun cured, they are tightly packed ent inventio'ro provide an -improved process i'or in hogsheads and aged in warehouses `lfor several rapidly and inexpensively increasing the moisture years. During aging, the tobacco vbecomes so content of tobacco accurately by any desired dry and brittle that it cannot be stemmed or amount. Another object o'f-the invention is the 2 handled, in fact can not be taken from the hogs- Y provision of a process in which the moisture conheads or otherwise disturbed, without shattering tentl oi.' the. tobacco can 'be raised t9v the exact the leaves and rendering itunnt for use. 'I'he op` point desired while the tobacco remains packed eration known as fordering" is a moistening in the aging hogsheads', whereby shattering or 30 treatment designed to, increase the moisture con# other injury to the tobacco leaves due to repeated 30 tent of aged tobacco to a point where it can be handling is avoided. A further objectof the inunpacked and stemmed without destructive shatvention is the provision of a process for extermitering` Y l' i nating pests, such asthe tobacco weevil or other L It has heretofore been the practice to moisten organisms found in tobacco, which PIOceSS 6f- 33 tobacco for stemming and handling by iii-st placi'ectively kills the eggs of the organisms as well as 35 ing' the hogsheads yof dry aged` tobacco in sweat the worms or insects. Other objects and advanrooms maintained at a temperature oi about tages ,of the process will become apparent from 110 F. and a relative humidity near the satura the appended detailed description. tion point (say about 95%) for a'perioc or several' In "general, the process 0f the invention in- '40 days. 'This increases the moisture content to anvolves rst subjecting tobacco to a high degree 40 extent such that the tobacco can be unpacked of vacuum whereby a large proportion oi' the air from the hogsh'eads without excessive breakage contained inthe structure is removed, then re- Vof the leaves although some loss results. The ducing the degree of vacuum while supplying to sweat room operationV does not within a reasonthe tobacco an amount o! steam somewhat in able time supply sumcient moisture to permit the excess of that required to produce the desired nal 45 stemming of the tobacco leaves, and accordingly moisture content, and thenagain increasing the A after the leaves are^unpacke`d from tle hogsheads 'Vacuum 0n the @Obacw whereby the excess mOiS- they are steamed until the moisture content has ture is evapolted and Bt least 8- Dl't 0f the heat increased to a /value at which the stemming opsupplied by the steam is absorbed. 'I'he ilnal step 5o' eration can be performed. Y insures that immediately after the steam treat- 50 The above-described known tobacco moistening ment, the tobacco is cooled to a safe tempera process requires the provision of large expensive ture. The entire process can be completed in a sweat rooms and involves tying up considerable matter of minutesand accordingly a large quanquantities of tobacco for extended The tity of tobacco can be treated withv comparatively known'process entails a steaming operation after smalland inexpensive apparatus. Our process is 55 applicable to tobacco in veither the packed or moistening can. be carried out very rapidly withthe unpacked state, and by the use of the process the tobacco may remain undisturbed in aging hogsheads or other containers until it has been moistened to the exact degree at which the subsequent stemming or other operations can best be performed. In this manner, the process avoids shattering or other injury to the tobacco leaves due to handling when the moisture content is low.

above about 125 F. for extended periods, it be-4 comes discolored and often moulded or rotted, probably due to the decomposition of,` oils or other substances in the leaves. However, tobacco will stand temperatures of 180 F. or even higher for periods of ten or fifteen minutes, and proportionately higher temperatures for shorter intervals .without discoloration 'or other detrimental change. In our process, the steam introduced to meisten the tobacco increases the temperature thereof as it condenses on the leaves,but the moistening step of the process is very short, and immediately thereafter the entire` mass of packed tobacco is rapidly cooled by vacuum evaporation of the excess moisture to a safe temperature. 'I'hus with our process the out injury to the tobacco and it is not necessary to unpack and cool the treated tobacco to prevent heat deterioration thereof. The final temperature of the tobacco after completion of our process may be varied as desired and is preferably well below 125 F., at which temperatures the tobacco can remain .indefinitely without deterioration.

We 'have discovered that by the application of our vacuum process, organisms which infest tobacco, in the form of larvae, pupa or beetle, as well as the eggs of such organisms, maybe killed. This may be accomplished as the result of the tobacco mcistening process referred `to above, or,

r1f it is desired to exterminate theests without altering the'moisture content, this can be readily accomplished by continuing the final vacuum evaporation at a value of vacuum or for a time -such that themoisture content of the tobacco is reduced'to its initial value. The extermination of pests without substantial net change in the moisture content is particularly desirable when the tobacco is to be stored for extended periods after the extermination, since in such cases a -ber or bell I removably mounted on'- a platform or base plate 2, together with means for evacuating the chamber and for admitting steam thereto. The vacuum chamber shown comprises a bell or inverted -air' `tight chamber, the lower edges of which rest on a gasket 3 carried by the base plate 2. With this arrangement, the bell 'I may be readily lifted to permit the insertion and removal of tobacco. 'I-wo tobacco hogsheads 4 have beenrepresented within `the bell I.

Lowi pressure steam may be applied to the interior of the bell I .through a pipe 5 under'the If tobacco is maintained at temperaturesl provided in the steam pipe 5 for measuring or' metering the quantity of steam admitted to the vacuum bell'during the process. Such a device has beendiagrammatically represented at 1, and

. suction pipe 9 Ieadingto the interior of the bell I through the plate 2. A` control valve I8 is preferably provided in the suction pipe 9. The evacuator illustrated includes a rst stage steam jet booster I0, an intercondenser Il, a second stage steam.jet booster I2, a second intercondenser I9 and a third stage steam jet booster 20. The number of stages of evacuating boosters may be increased or decreased, and the invention is in no way limited to the use of the three-stage apparatus illustrated. Since multi-stage steam provided for controllably jet evacuators of the `type illustrated are well known in the art, and since the invention is in no way hunted to the use of the particular evacuator illustrated, a detailed descriptionof theconstruction thereof will not be given.

The vacuum or absolute pressure within the bell I is indicated by a suitable gauge I4 and the temperature by a thermometer I5. able means are provided for admitting air to break the vacuum within the bell I, and, as shown, a pipe I6 passing through the base plate 2 and controlled' by the valve I1 maybe em.- ployed for this purpose.

The process of the invention may be employed to increase the moisture content at various stages during the preparation or shipment of to- .bacco,'and is in no way limited to any particular phase of tobacco treatment. The process is particularly useful in connection with preparing aged and dry tobacco for unpacking an'd stemming, and accordingly will be described in this connection. 4

The aged tobacco, packed in hogsheads I, is placed on the base plate 2 withinv the gasket 3 and the bell I isseated on thegasket over the hogsheads als` shown in the drawing. The heads may be removed fromthe"h2ogsheads before treatment it desired, but this operation is not suitessential since the hogsheads are not fluid tight. g

vWith the valves B and lII closed and the valve I8 open, the evacuator operated until a high vacuum is produced. The tobacco is' maintained under this high vacuum for a few minutes to permit substantially complete removal of air therefrom. With valves l1 and' I8 still closed, a

quantity of low pressure steam is admitted to the bell'I from the pipe 5,*the amount admitted being regulated by the valve 6. The initial inrush ofthe steam lowers tlievacuum, and thereafter the ycondensation of the .steam maintainsthe lower vacuum substantially constant.

Prior 'to rthe moistemng treatment, the :maar Y moisture content of the tobacco is determined in any suitable known manner. The amount of steam required to increase this initial moisture content to that desired is then calculatd or determined by tests, and the amount of steam admitted to the bell I as described above is regulated to ,exceed this required amount by a known margin.

v desired final moisture content of about 14%. the

amount oi steam admitted may be such as will supply an amount of moisture from 20% to 30% inexcess of the quantity required to give the desired nal moisture content.

,During the admission of the steam, the vacuum:

on the tobacco is reduced, and at the same time, the tobacco is heated to a high temperature, well above 125 F., and which may be as high as 160 F. or even higher. If the tobacco were allowed to remain at such a high temperature for any con- .siderableflength of time, it would be discolored and otherwise deteriorated by the heat.. According to the present process, however, the steaming process is immediately followed by a final vacuum evacuating stage which not only extracts the excess moisture present, but, also cools the tobacco by vacuum evaporation to a safe low temperature which is appreciably below 125 F.

' When the predetermined amount of steam has been admitted, the valve I is closed, suction valve I 8 is opened and the vacuum in the bell I is increased. 'I'hls causes the rapid evaporation of the excess moisture from the tobacco and thus refrigerates and cools the tobacco due to the absorption of heat during the vacuum evaporation. When themoisture content has been reduced to the desired iin-a1 value, the temperature oi the tobacco will have dropped to a safe low value, at this point 'the'valve i8 is closed, and the vacuum is broken by opening the air valve I1, completing the process. The evaporatixig `step is rapidly performed and in many cases may be completed-in three or four minutes. After the vacuum is broken the bell I is removed from the base plate 2, the .treated hogsheads are removed and other hogsheadsior treatment are placed on the plate andprocessed as deseribed above.

We-have found thatthe degreer of'svacuum which should be employed in the initial evacuating stage of the process is somewhat dependent upon the temperature of the tobacco, and should; i in general, be increased when the initial temperature ofgthe tobacco is low. Under normal conditions, when theaprocess isemployed to'a lot o`f tobacco, the mass oi* which has an initial minimum temperature of about 50 F., theinitial high vacuum may beabout 29.65 inches of mercury or slightly higher. 'Whenthe tobacco isv colder,`

higher values of'vacuum must be used-in the initial evacuating stage, and under extremely iow temperature' conditions, anl initial vacuum of `29.85 inches of mercury or. even higher may be the necessary evacuation.

The point' at which the vacuum isbroken and the process terminated may be determined by the temperature within the vacuum, bell I as indicated by the therrnoz'neter I5. The amount of.V excess moisture present, thedegree or under which the'final evaporationvtakes place and the initial temperature within the bell may bevmaintained at the same values during the treatment oi' successive lots of tobacco, and under time cir# a minimum amount voi labor, the tobacco remainn ing undisturbed in the aging liogsheads until after other heat deterioration can take place. In car- Y cumstances, when the moisture content is reduced to vthe desired point the temperture in the beu will reach a definite value which can be determined by calcuiation or test ior any given set or conditions. The value of vacuum employed in the final evacuating stage'may be varied between wide limits in accordance with the amount of moisture added by the steaming operation and the final moisture content desired. In general, where moisture is to be added, the iinal increase of vacuum is not suiilcient to bring the vacuum back to its initial height. When the process is employed for the extermination of pests and it is" desired to restore the tobacco to its initial moisture content, the increase, in vacuum employed in the flnal evaporating stage may be suilicient to reach the initial vacuum.

In applying our process to the extermination of pests, such as the cigarette beetle, the tobacco may be treated in the manner described above in connection with the addition of moisture. Thus the tobacco 'is successively subjected to an initial high vacuum, then to an application of steam under reduced vacuum whereby the tobacco temperature is raised to aA value well above F. and preferably in the neighborhood of F; or higher, and nally subjected to a vacuum higher A than the steaming vacuum and sufilcient to lower the tobacco temperature to a value at which heat deterioration can not take' place. The extermination of the pests may be accomplished concurrently with the addition of moisture to the tobacco, or, as explained above, the moisture content may be restored to its initial value so that after extermination the tobacco may be' stored indeilnitely without moulding or other deterioration due to excess moisture. 'I'he exterminating operation is very inexpensive and highly effective, killing not only the larvae, pupae andA insects present, but 4also the eggs which are usually deposited in the tobacco structure.

Our process is carriedout very rapidly and with the process has vbeen completed. By -employing an initial high vacuum and reducing' this vacuum while treating the tobacco with the steam, the moistening'loperation can be completed in a few minutes. The introduction of excess moisture nand its subsequent evaporation under vacuum reducesthe temperature oi the tobacco to a salle value long before any discoloration or rying' out the process asA described above, the tobacco is subjected to temperatures in excess of 125 F. for avperiod oi only a -i'ew minutes, and

accordixiglf all danger of@ deterioration due to prolonged hi h temperatures is avoided.

It should understood that the invention, in yits broader aspects, is not limited to the particular values of temperature, pressure, time and mbis- LA process formoistening. tobacco comprising 70 4iirst subjecting the tobacco V.to a relatively high vacuum; then supplying steam to thev tobacco while reducing the vacuum' thereon, and then as a .ilnal-step subjecting'the tobacco to an increased vacuum until it has beencooled by evaporation 'IIS- v uum until the moisture content thereof has been reduced by vacuum evaporation to the Idesired value, whereby some of the heat supplied to the tobacco bythe' steam is immediately absorbed .by the evaporating moisture, and no perceptible change of color of the'tcbacco takes place.

3. A .process for increasing the moisture content of tobacco to a predetermined value which comprises subjecting the tobacco to a relativelyl high vacuum, reducing the vacuum on the tobacco and supplying thereto, while under such lower vacuum, an amount of vsteam sulcient to supply moisture in an amount froml20% to 30% in excess of that necessary to produce the desired4 predeterminedvalue, and then subjecting'the tobacco to an increased vacuum until the temperature thereof has been `lowered below that at which heat deterioration 'can take place and the excess moisture has been evaporated.

4. A process for increasing the moisture content of'gtobacco to a predetermined value which comprises subjecting the tobacco to a relatively high vacuumreducing the vacuum on the toybacco and"supplylng thereto, while undersuch lower vacuum, an amount of steam sulcient to supply moisture in an amount from 20% to 30% in excess of that necessary to produce the desired predetermined value, and then maintaining the tobacco under vacuum o! suilicient height that while the 'excess moisture is evaporated. the temperature ofthe tobacco will belowered to a value below 125 F. f

5. A process for increasing the moisture con-4 Atent of tobacco which comprises subjecting the tobacco to a high vacnumfinaihtaining the tobacco under lower vacuum while supplying thereto a quantity of steam'sufilcient to supply moisi ture in excess of the amount desired,l and then obtainin subjecting the tobacco to high vacuum until the temperature of .the tobacco has beenlowered be- .low that at which heat deterioration, can take.

evaporation of the excess mioisplace by vacuum ture.

6. A process for moiteningtobacco to 8. predetermined degree whichI comprises subjecting the tobacco to an initial high vacuum, supplying steam to the tobaccoV while decreasing the degree of vacuum to' which it is subjected, the total amount of steam so supplied being lin excess to that required to bring the moisture content oi' the tobacco to the desired point', and then sublecting the tobacco to a vacuum higher than that while the steam was supplied thereto but app iably lower than saidinitial high vacuum, whereby the excess moisture is vevaporated 4and the tobacco is cooled, and no perceptible change of color 'ot the tobacco takes place.

7. A process for increasing themolsture content of tobacco which comprises subjecting the tobacco to a high initial vacuum, maintaining the tobacco under lower vacuum while supplying thereto a quantity o! steam sulcient to -supply moisture in excess of the amount desired. and then subjecting thetobacco to a vacuum higher than that to which it wassubiected wnue the 'supplied thereto but appreciably low- Awhereby no perceptible change of colo er than said high mitici vacuum until the temperature of the tobacco has lbeen lowered by vacuum evaporation of the excess moisture to a value at which heat deterioration cannot take place.

8. A process for moistening tobacco comprising successively subjecting the tobacco to a high vacuum, supplying steam to the tobacco while reducingy the vacuum thereon and then as a inal step increasingthe vacuum to a value sucient to-cause evaporation of at least some of .the moisture supplied to the tobacco by the steam,.whereby no perceptible'change of color of the tobacco takes place.

9. A process for exterminating organisms in tobacco comprising subjecting the tobacco to a high vacuum, simultaneously supplying steam tol 'tobacco comprising subjecting the tobacco to a high vacuum, supplying steam to the tobacco4 While reducing the vacuumthereon whereby thev tobacco is heated to a temperature at which heat deterioration would takefplace after a time nter- Val, and, as a iinal step prior to the expiration of such interval, increasing the vacuum on the tobacco to a value such that its temperatureis reduced below that at which heat deterioration takes place.

11. A vprocess for increasing the moisture content of tobacco by a predetermined amount which comprises rst subjecting the tobacco to a vacuum from 28 to 29% inches of mercury, then l reducing the vacuum by 8 to 10 inches of mercury and maintaining the vacuum at such intermediate value while supplying to the tobacco an 'amount of steam sumcient to incease'the moisture content of the tobacco by'an amount from 20% to 30% in excess of the, increasedesired, and then subjecting the tobacco to an increased vacuum oi.' from 28 to 291/2 inches of mercury until the excess moisture is evaporated and the temperature of the tobacco is reduced below 120 F. .f

- 12. A process for moistening tobacco compristhe vacuum on the tobacco suillciently to cause evaporation of some of the moisture supplied to so applied, and then as a final step increasing the tobacco by the steam, whereby no perceptible 1 change of color o f-the tobacco takes place, the

tobacco being maintained at sub-atmospheric pressure throughout the process.

13. A process for moistening a mass of tobacco comprising subjecting the tobacco to a high vac-l uum. then supplying steam to the tobacco while reducing the vacuum thereon to a sub-atmospheric pressure suillciently in excess o1 the initial high vacuum to cause penetration of the steam throughout the tobacco mass, and then as a 14. A process' for increasing the moisture con- 75 mainiinal step increasing the vacuum on the tobacco tent of tobacco comprising subjecting the tobacco to a high vacuum, then reducing the vacuum on the tobacco while supplying sufficient steam thereto to heat the tobacco to a temperature at which heat deterioration. thereof would take place after a time interval, and then prior to the expiration o f such interval increasing the vacuum on the tobacco sufficiently to cause evaporation of some of the moisture supplied to the' tobacco by the steam, whereby the tobacco is cooled by such evaporation to a temperature at I which heat deterioration thereof cannot take would take place after a time intervahand then prior to the expiration of such interval increasing the vacuum on the tobacco sufficiently to` cause evaporation of such a part of the moisture supplied to the tobacco by the steam that the tobacco temperature is reducedby such evaporation to a value at which heat deterioration of the Cri tobacco' vcannot. take place.

16. A process for moistening tobacco which comprises rst subjecting the tobacco to a vacuum of at least 28 inches of mercury, then reducing the vacuum while supplying. to the tobacco an amount of steam sufficient to increase the moisture content of the tobacco by an amount invexcess of the nal increase desired, and then increasing the vacuum on the tobacco to a value lower than 28 inches of mercury until the excess moisture is evaporated and the temperature of the tobacco is reduced to at least 125 F.

1'7. A process for increasing'the moisture con tent of tobacco comprising subjecting the to-v bacco to a high vacuum, then reducing the. vacuum on the tobacco while supplying suilicient steam thereto to heat the tobacco to a temperature at which heat deterioration thereof would take place 'after a given time interval, and then prior to the expiration of such interval increasing the vacuum on the tobacco suiliciently to cause evaporation of some of the moisture supplied tothe tobacco by the steam, whereby the tobacco is cooled by such evaporation to a temperature at which heat deterioration thereof cannot take place within an interval appreciably greater than said given time interval.

18. A process for increasing the moisture content of a mass of tobacco comprising subjecting the tobacco to a high vacuum, then supplying steam to the tobacco while reducing the vacuum thereon to a sub-atmospheric pressure sufficient- 1y in excess of the initial high vacuum to cause penetration of the steam throughout the tobacco mass, whereby the tobacco is heated toa temperature at which heat deterioration thereof would take place after a given time interval, and then prior to the expiration of such -interval increasing the vacuum on the tobacco sufliciently to cause evaporation of such a part of the mois ture supplied tothe tobacco by the steam that the tobacco temperature is reduced by such evaporation to a value at which heat deterioration of the tobacco cannot take place Within an interval appreciably greater thansaid given time interval.

19. A process for exterminating organisms in tobacco comprising subjecting the tobacco to a high vacuum, supplying steam to the tobacco while reducing the vacuum thereon whereby the tobacco is heated to a temperature at which heat tion of such interval, increasing the vacuum on 

